The present invention is drawn to ink-jet inks, systems, and methods for secure ink-jet printing on documents.
In recent years, computer printer technology has evolved to a point where very high-resolution images can be transferred to various types of media, including paper. One particular type of printing involves the placement of small drops of a fluid ink onto a media surface in response to a digital signal. Typically, the fluid ink is placed or jetted onto the surface without physical contact between the printing device and the surface. Within this general technique, the specific method that the ink-jet ink is deposited onto the printing surface varies from system to system, and can include continuous ink deposit and drop-on-demand ink deposit.
With regard to continuous printing systems, inks used are typically based on solvents such as methyl ethyl ketone and ethanol. Essentially, continuous printing systems function as a stream of ink droplets are ejected and directed by a printer nozzle. The ink droplets are directed additionally with the assistance of an electrostatic charging device in close proximity to the nozzle. If the ink is not used on the desired printing surface, the ink is recycled for later use. With regard to drop-on-demand printing systems, the ink-jet inks are typically based upon water and glycols. Essentially, with these systems, ink droplets are propelled from a nozzle by heat or by a pressure wave such that all of the ink droplets ejected are used to form the printed image.
There are several reasons that ink-jet printing has become a popular way of recording images on various media surfaces, particularly paper. Some of these reasons include low printer noise, capability of high speed recording, and multi-color recording. Additionally, these advantages can be obtained at a relatively low price to consumers. However, though there has been great improvement in ink-jet printing, accompanying this improvement are increased demands by consumers in this area, e.g., higher speeds, higher resolution, full color image formation, increased stability, new applications, etc. As new ink-jet inks are developed, there have been several traditional characteristics to consider when evaluating the ink in conjunction with a printing surface or substrate. Such characteristics include edge acuity and optical density of the image on the surface, dry time of the ink on the substrate, adhesion to the substrate, lack of deviation of ink droplets, presence of all dots, resistance of the ink after drying to water and other solvents, long term storage stability, and long term reliability without corrosion or nozzle clogging. Though the above list of characteristics provides a worthy goal to achieve, there are difficulties associated with satisfying all of the above characteristics. Often, the inclusion of an ink component meant to satisfy one of the above characteristics can prevent another characteristic from being met. Thus, most commercial inks for use in ink-jet printers represent a compromise in an attempt to achieve at least an adequate response in meeting all of the above listed requirements.
In general, ink-jet inks are either dye- or pigment-based inks. Dye-based ink-jet inks generally use a soluble colorant that is usually water-based to turn the media a specific color. Alternatively, pigmented inks typically use a dispersed colorant to achieve color. In many cases, the line quality and accuracy of plots produced by pigment-based inks can be superior to that of dye-based inks. However, certain challenges exist with pigments because the colorant is present as a dispersion. With pigmented inks, solid particles are jetted with a vehicle and the solid particles adhere to the surface of the substrate. Once the water in the solution has evaporated, the particles will generally not redisperse, thereby producing a dried image.
Documents having a need to be marked as official or original, such as identity cards, passports, banknotes, checks, bonds, and the like have become an important part of business. Particularly, in light of new technological advances, more and more interest in marking documents as original has followed. In the prior art, methods using items such as threads, fibers, colored elements, metallized elements, magnetized elements, or filigranes have been provided with reasonable success. Specifically, some of the methods of the prior art used to prevent copyability of documents include papers coated with a cacao-colored layer, the use of special inks printed on a masking background, colored films coated on semi-transparent vacuum-metallized films, and security papers based on dark pigments covering the sensitivity spectrum of modern photocopiers. However, in this area, there is a need for additional technologies that provide similar results, while at the same time provide people at the consumer level to easily and readily have access to original document marking technology using relatively simple equipment.
It would be desirable to provide inks, particularly for use in ink-jet ink printers, that are useful for providing visible, non-copyable markings on documents to denote that they are original documents. It would also be desirable if these and other inks could be used as part of systems and methods related to the area of original document marking.
With this in mind, a specialty ink-jet ink can comprise an ink vehicle; and a sufficient amount of particulates having directionally dependent light reflective properties within the ink vehicle such that when the ink-jet ink is substantially dried on a desired substrate, a multi-colored reflected light is emittable in the presence of a light source. Additionally, an aqueous ink-jet ink printing system can comprise a specialty ink-jet ink having an effective amount of particulates contained therein, wherein the particulates have directionally dependent light reflective properties; and a specialty ink-jet ink pen configured for jetting the ink-jet ink.
Several methods can also be implemented using the inks of the present invention, as well as other inks that impart non-copyable properties. For example, a method for marking a document as an original can comprise the steps of providing an image-containing document that is to be marked as an original; and ink-jetting a visible mark onto the document, wherein the visible mark has a non-copyable property. Alternatively, a method of generating revenue can comprise providing a specialty ink-jet ink pen for use in a printer, wherein the specialty ink-jet pen is capable of printing a visible mark on a substrate, and wherein the visible mark has a property that is non-copyable; and limiting the number of substrates that can be printed with the specialty ink-jet ink pen in accordance with an amount of consideration paid by the customer. Further, a method of providing clients with original document marking services can comprise obtaining a document on which a client wishes to have marked as original; and printing a visible mark on the document, wherein the visible mark is non-copyable. The non-copyable visible mark preferably exhibits directionally dependent light reflective properties.